return NULL;
}
-/*
- * look for an offset in the tree, and if it can't be found, return
- * the first offset we can find smaller than 'offset'.
- */
-static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
-{
- struct rb_node *prev;
- struct rb_node *ret;
- ret = __tree_search(root, offset, &prev, NULL);
- if (!ret)
- return prev;
- return ret;
-}
-
/* check to see if two extent_map structs are adjacent and safe to merge */
static int mergable_maps(struct extent_map *prev, struct extent_map *next)
{
write_lock(&tree->lock);
em = lookup_extent_mapping(tree, start, len);
- WARN_ON(em->start != start || !em);
+ WARN_ON(!em || em->start != start);
if (!em)
goto out;
return em;
}
+/**
+ * search_extent_mapping - find a nearby extent map
+ * @tree: tree to lookup in
+ * @start: byte offset to start the search
+ * @len: length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range.
+ *
+ * If one can't be found, any nearby extent may be returned
+ */
+struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len)
+{
+ struct extent_map *em;
+ struct rb_node *rb_node;
+ struct rb_node *prev = NULL;
+ struct rb_node *next = NULL;
+
+ rb_node = __tree_search(&tree->map, start, &prev, &next);
+ if (!rb_node && prev) {
+ em = rb_entry(prev, struct extent_map, rb_node);
+ goto found;
+ }
+ if (!rb_node && next) {
+ em = rb_entry(next, struct extent_map, rb_node);
+ goto found;
+ }
+ if (!rb_node) {
+ em = NULL;
+ goto out;
+ }
+ if (IS_ERR(rb_node)) {
+ em = ERR_PTR(PTR_ERR(rb_node));
+ goto out;
+ }
+ em = rb_entry(rb_node, struct extent_map, rb_node);
+ goto found;
+
+ em = NULL;
+ goto out;
+
+found:
+ atomic_inc(&em->refs);
+out:
+ return em;
+}
+
/**
* remove_extent_mapping - removes an extent_map from the extent tree
* @tree: extent tree to remove from